An adapter, also known as a power adapter, is used to charge a device to be charged (e.g., a terminal). An adapter currently available on the market typically provides a constant voltage to charge the device to be charged (e.g., a terminal). When the current drawn by the device to be charged (e.g., a terminal) exceeds the maximum output current threshold the adapter can supply, however, the adapter may be triggered to enter the overload protection state such that the device (e.g., a terminal) would no longer be charged.